JPS63223490A - Intermediate heat exchanger - Google Patents

Abstract

PURPOSE:To enable the distribution of flow rate of a primary cooling medium to be uniformly made through a thermal conduction pipe via an upper plenum by a method wherein a flow regulator is arranged in which the flow rate of the medium may be controlled in such a way as a large volume of primary cooling medium may be flowed to a central part of the upper plenum from an inlet window of a plenum barrel to a pipe plate. CONSTITUTION:A flow regulator plate 24 covering the entire area of cross section of an upper plenum 14 is arranged near a lower part of an inlet window 15 of a plenum barrel 1. This flow regulator plate 24 is formed with several through-holes 25 and an upstream side and a downstream side within the upper plenum 14 interconnected through the through- pass holes 25. Primary cooling medium flowed from an inlet window 15 at a plenum barrel 1 enters the through-pass holes 25 before reaching the downstream side within the upper plenum 14 and is flowed toward the inner side of an annular row of auxiliary cooling thermal conducting pipes 16 increasing a flow rate of the medium, but is not flowed outside of the annular row of the thermal conducting pipes of which flow rate is restricted. Flow along an inner periphery of the plenum barrel is diminished by a flow directing toward a center of the upper plenum, thereby a variation of flow rate between near the inlet window 15 and a pressure area spaced part from the inlet window is not generated and a uniform distribution of flow rate at the thermal conducting pipe 11 fed afterwards is established.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an intermediate heat exchanger for a fast breeder reactor, and particularly to an intermediate heat exchanger used in a tank-type fast breeder reactor.

(Conventional Technology) Fast breeder reactors, which are expected to be the next generation nuclear reactor for power generation, are currently in the process of being developed for practical use, and research is actively underway in various fields. Depending on the reactor type, fast breeder reactors are broadly divided into tank type and loop type. Of these, tank type fast breeder reactors house the reactor core, secondary cooling system main circulation pump, and intermediate heat exchanger in a large tank-shaped container. Compared to the loop type, the structure is simpler and more economical, and it also has the advantage of preventing leakage of coolant to the outside even in the event of a rupture of the piping of the secondary cooling system.

In general, fast breeder reactors have a double loop in which the heat generated in the reactor core is received by the coolant in the primary cooling system (usually liquid sodium) and transferred to the coolant (feed water) in the secondary cooling system. It is formed.

The intermediate heat exchanger is a device that exchanges heat between these double loops, and as mentioned above, in a tank-type fast breeder reactor, it is placed adjacent to the reactor core that occupies the center of the vessel.

Hereinafter, an outline of a conventional intermediate heat exchanger will be explained with reference to FIG. 4. That is, the intermediate heat exchanger includes a cylindrical plenum shell 1 and a main body shell 2 that is integral with or continues integrally with the plenum shell 1, and is fixed to the roof slab 4 with an installation flange 3 formed at the upper end. It is suspended and supported within the reactor vessel (not shown).

A downcomer pipe 5 is concentrically provided in the center of the main body shell 2, and this downcomer pipe 5 extends above the roof slab 4 through the center of the plenum shell 1, and the upper part of the downcomer pipe 5 is provided with a secondary coolant. The population is 6. A rising pipe 7 is provided between the downcomer pipe 5 and the Blenheim shell, and an annulus section 8 between the downcomer pipe 5 and the rising pipe 7 serves as a flow path for secondary coolant. Further, a secondary coolant outlet 9 is provided near the top of the riser pipe 7, and a heat shield 10 is installed between the riser pipe 7 and the roof slab 4 to block heat and radiation radiated from the primary coolant. has been done.

On the other hand, a large number of heat transfer tubes 1] are arranged in the vertical direction between the downcomer pipe 5 and the main body shell 2, and between an upper tube plate 12 and a lower tube plate 13 connected to the upper and lower parts of the heat transfer tubes 11. A heat exchange section is formed.

The space formed by the upper tube plate 12, the heat shield 10, the plenum shell 1, and the riser pipe 7 is called the upper plenum 14, and the primary coolant flows into the space through the inlet window 15 provided in the plenum shell 1. , a free liquid level (
It has a structure that forms a structure (indicated by NSL in the figure). Inside this upper plenum 14, there are many auxiliary cooling heat exchanger tubes 1.
6 and headers 17a and 17b are housed therein.

Furthermore, the area outside the upper plenum 14 separated by the plenum shell 1 and the main body shell 2 is called a hot pool 18, and the area below this hot pool 18 separated by a separator 19 is called a cold pool 20.

In addition, the reference numeral 21 in the figure is a lower plenum, and
Reference numeral 23 indicates a flow skirt.

In the above configuration, the primary coolant led to the hot pool 18 passes between the plenum body 1 and the flow skirt 23 as shown by the white arrow in the figure, enters the upper plenum 18 through the artificial window 15, and then enters the upper plenum 18 through the artificial window 15. The temperature is lowered by exchanging heat with the secondary coolant guided into the heat transfer tube 11 and flowing outside thereof. After this, −
The secondary coolant passes through the lower plenum 21 and the primary coolant outlet 22
It is sent to the cold pool 20.

On the other hand, the secondary coolant flows from the secondary coolant inlet 6 as shown by the black arrow in the figure, passes through the downcomer pipe 5, reaches the lower tube plate J3, where it reverses and flows upward, and flows into the heat exchanger tube. The temperature is increased by exchanging heat with the primary coolant flowing inside the tube. Thereafter, the secondary coolant passes through the annulus portion 8 and is sent from the secondary coolant outlet 9 to a steam generator (not shown).

Furthermore, when the operation of the secondary cooling system is stopped, the auxiliary cooling system works to remove heat from the primary cooling system.

That is, during normal operation, the auxiliary coolant circulating in the auxiliary cooling system fills the header 17a, which is maintained at a constant pressure. At this point, if the secondary cooling system stops.

The auxiliary coolant flows from the ladder 17a to the auxiliary cooling heat exchanger tubes 16, and the primary coolant staying in the upper plenum 14 loses heat to the auxiliary coolant and is lowered in temperature. After this,
- The auxiliary coolant, whose temperature has increased due to heat exchange with the secondary coolant, is once collected in the ladder 17b, and from there is sent to an air cooler (not shown) for cooling.

An example in which the heat exchange section of the auxiliary cooling system is installed within the intermediate heat exchanger is described in Japanese Patent Application Laid-Open No. 60-53787.

(Problems to be Solved by the Invention) By the way, in such a conventional intermediate heat exchanger, the heat transfer area of the auxiliary cooling system is ensured by the auxiliary cooling heat transfer tubes 16 forming an annular row within the upper plenum 14. be done. In this case, these auxiliary cooling heat transfer tubes 16 need to be arranged quite densely as shown in FIG. It is obstructing the flow. In other words, as shown by the arrow in FIG. Also flows between the inner periphery of the plenum shell 1 and the outer periphery of the annular row of heat exchanger tubes 16 for auxiliary cooling. For this reason, the flow rate of the primary coolant flowing into the annular row of the auxiliary cooling heat transfer tubes 16 becomes non-uniform in the circumferential direction, and a flow toward the center of the annular row is not formed at a portion away from the inlet window 15. , a significant deviation occurs in the meteor distribution of the primary coolant flowing into each heat transfer tube 11. This imbalance in flow rate distribution may cause buckling between the heat transfer tubes 1 due to the difference in thermal expansion, leading to damage.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an intermediate heat exchanger that can maintain uniform flow distribution of primary coolant dedicated to each heat transfer tube.

[Structure of the invention]

(Means for Solving the Problems) An intermediate heat exchanger according to the present invention includes a tube plate covering the bottom of the plenum shell to form a two-part plenum, and an annular row of heat transfer tubes housed in the upper plenum. In the intermediate heat exchanger that constitutes the heat exchange section of the auxiliary cooling system, the flow rate is adjusted so that more heat exchange medium flows through the center of the upper plenum from the artificial window of the plenum shell toward the tube plate side. The device is characterized by being equipped with a device.

(Function) The primary coolant flowing into the upper plenum through the inlet window of the plenum shell is directed more toward the inner side of the annular row of heat transfer tubes by a rectifier whose flow rate is adjusted to control the outer region, with more in the center. flow, but does not flow outside the annular array. This flow toward the center of the upper plenum eliminates flow along the inner circumferential surface of the plenum body, preventing flow imbalance between the vicinity of the inlet window and areas remote from it, and preventing subsequent flow. Flow distribution in the heat tubes is made uniform.

(Example) An example of the present invention will be described with reference to FIGS. 1 and 2.

In this embodiment, the same parts as those shown in FIGS. 5 and 6 are designated by the same reference numerals, and the explanation thereof will be omitted.

In FIG. 1, a rectifier plate 24 is provided near the bottom of the inlet window 15 of the plenum body 1 to cover the entire cross section of the upper plenum 14. As shown in FIG. 2, this current plate 24 has a large number of through holes 25 formed therein, through which the upper and lower regions of the upper plenum 14 are connected. Here, the opening area of the through hole 25 is determined so that the flow rate is large in the center of the rectifying plate 24 and meteors are suppressed in the outer region.

According to the above configuration of the embodiment, the entrance window 15 of the plenum shell 1
The primary coolant flowing further enters the through hole 25 before reaching the lower region in the upper plenum 14 and flows inward of the annular row of auxiliary cooling heat transfer tubes 16 increasing the flow rate, thereby suppressing the flow rate. It does not flow outside the annular row. This flow toward the center of the upper plenum eliminates the flow along the inner circumference of the plenum body.

As a result, there is no deviation in the flow rate between the vicinity of the inlet window 15 and the pressure reduction part far away from the inlet window 15, and uniformity of flow rate distribution in the heat exchanger tubes 11 introduced thereafter is achieved.

Therefore, the difference in thermal expansion between the heat exchanger tubes 11 is reduced, and the risk of damage due to buckling is eliminated.

Next, another embodiment of the present invention will be described with reference to FIGS. 3 and 4.

In FIG. 3, this embodiment uses the inner periphery of the plenum shell 1 and the auxiliary cooling heat exchanger tube 1 instead of the rectifying plate 24 in the above embodiment.
baffle plate 2 that covers only the annular space between the annular row outer periphery of No. 6;
6 is provided. Here, the baffle plate 2 is attached to the inner circumferential surface of the plenum shell 1 so as to secure a certain gap between it and the outer circumference of the annular array of auxiliary cooling heat transfer tubes 16 (see Fig. 4).
.

In this embodiment, the flow of the primary coolant in the upper plenum 14 is restricted outside the annular row of auxiliary cooling heat transfer tubes 16, and the flow along the inner circumferential surface of the plenum shell 1 is eliminated. As a result, uniformity of flow rate distribution in the heat transfer tubes 11 is achieved as in the above embodiment.

〔Effect of the invention〕

As explained above, the present invention is equipped with a rectifier that adjusts the flow rate so that more primary coolant flows from the inlet window of the plenum body toward the tube plate side, so that more primary coolant flows into the center of the upper plenum. It is possible to equalize the flow rate distribution of the primary coolant that is guided through the heat exchanger tubes.

Therefore, according to the present invention, an excellent effect is achieved in that damage accidents due to buckling of heat exchanger tubes are prevented.

[Brief explanation of the drawing]

Part 1 is a sectional view showing one embodiment of the intermediate heat exchanger according to the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a sectional view showing another embodiment of the present invention. 4 is a sectional view taken along line IV-IV in FIG. 3, FIG. 5 is a sectional view showing an intermediate heat exchanger according to the prior art, and FIG. 6 is a sectional view taken along line VI-VI in FIG.
It is a sectional view along a line. 1... Plenum shell 11... Heat exchanger tube 12...
・Upper tube plate 13...Lower tube plate] 4...Upper plenum 15...Inlet window 16...Auxiliary cooling heat transfer ￥f24...Buffer plate 25...Through hole
26... Jamaboard agent Patent attorney Nori Chika Ken Yudo Hirofumi Mitsumata JP-A 1FHG3'-223490 (6) Figure 6

Claims (2)

[Claims] (1) In an intermediate heat exchanger in which the bottom of the plenum body is covered with a tube plate to form an upper plenum, and an annular row of heat transfer tubes is accommodated in the upper plenum to constitute a heat exchange section of an auxiliary cooling system. An intermediate heat exchanger, characterized in that a flow rectifier is provided which adjusts the flow rate so that more heat exchange medium flows from the inlet window of the plenum shell toward the tube plate side to the center of the upper plenum. (2) The intermediate heat exchanger according to claim 1, wherein the rectifying device is a rectifying plate having a large number of through holes in the center thereof.